I agree, if your going to keep that processor. If you were going to run a haswell system with that gpu, a low wattage psu would probably work. But if your just upgrading gpu, Then yes, more wattage would probs be a good thing. Also, make sure that your Core 2 quad isn't going to bottleneck that gpu, I can imagine games like crysis 3 that it probably will. So maybe look into waiting and doing a full system upgrade, but I understand if moneys an issue (which come on it almost always is for all of us) then get a new gpu and psu, then look at doing cpu/motherboard upgrade farther down the road.
Edit: also if you dont have connectors, that would be an even bigger issue.